Supporting structure formed on high-ground-stress weak surrounding rock tunnel by using ultralong extended head anchor cable

Abstract

The invention discloses a supporting structure formed on a high-ground-stress weak surrounding rock tunnel by using an ultralong extended head anchor cable, and relates to the field of tunnel construction. The supporting structure comprises a supporting structure body and a primary supporting structure, wherein the supporting structure body comprises a hole formed in surrounding rock, an anchor cable and a grouting body filled in the hole; the anchor cable is divided into an anchoring section, a tensioning section and an outer anchor head; the cross section dimension of the anchor cable head positioned in the anchoring section is greater than other positions of the anchor cable; the anchor cable positioned in the tensioning section generates prestress when being tensioned; and the length of the anchor cable is 35 to 40m. The friction resistance of the surrounding rock on the anchoring section is transmitted to the primary supporting structure through the tensioning section; through theeffect of the prestress, the rock body structure surface is in a tightly pressed state, so that the integrality of the surrounding rock per se is improved; the anti-sliding force of the sliding surface is directly changed so as to maintain the stress balance of the surrounding rock; meanwhile, the cross section of the anchoring section is expanded, so that the expanded head and the rock body extrude to form strong end bearing force; and the pulling-resistant force is greatly improved, so that the goals of stabilizing deep surrounding rock and inhibiting the deformation can be achieved.

Description

technical field [0001] The invention belongs to the field of tunnel construction, and in particular relates to a supporting structure for a tunnel with high ground stress and weak surrounding rock by using super-long expansion-head anchor cables. Background technique [0002] High ground stress has a significant impact on geotechnical engineering, especially for underground projects with large buried depths and soft surrounding rocks, such as railway tunnels, highway tunnels, and deep-buried mining roadways. With the continuous development of my country's railway and highway construction, tunnel engineering has developed in the direction of growing and deep burial. Therefore, in recent years, long tunnel projects with weak surrounding rocks that pass through high ground stress areas and have harsh geological environments have emerged, such as the 8.5-kilometer Maoyushan Tunnel on the Lanzhou-Chongqing Railway, the 9.2-kilometer Xinchengzi Tunnel, and the 19.1-kilometer Muzha...

AI Technical Summary

Problems solved by technology

[0003] After excavation and support, the large-deformation tunnel with weak surrounding rock and high ground stress has strong extrusion and deformation of the surrounding rock, resulting in large-scale damage to the primary support, cracking of shotcrete, twisted and broken steel frames, and encroachment of side walls. The release in the surrounding rock tunnel is often a long-term and slow process, and it will also cause the secondary lining that has been prepared in the early stage to crack continuously in the later stage, requiring rework and renovation

Therefore, problems such as broken surrounding rock, large ground stress, and long release period lead to large convergence of tunnel construction deformation, frequent process changes and program changes, discontinuous construction and production, and low work efficiency, which seriously plague the construction schedule and construction safety.

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